Hitherto, a variable flow rate valve mechanism which adjusts a flow rate of a working fluid supplied to a turbine of a turbocharger is known (for example, see Patent Literature 1). The variable flow rate valve mechanism includes a bushing (a bearing) which is provided in a turbine housing accommodating a turbine, a stem which is rotatably supported by the bushing, a valve body which is connected to one end of the stem, and a link member which is connected to a base end of the stem and swings about an axis line of the stein by the driving of an actuator.